string_to_ip6 parses an IPv6 address from a string. Parsing v6 addresses
is a bit more complicated than parsing v4 because there are a number of
different formats that can be used.

Signed-off-by: Chris Packham <judge.pack...@gmail.com>

---
I'm sure the parsing can be better and done in less code with only a
single pass but I haven't yet figured it out. The main problem is that
"::" can represent a variable number of contiguous "0000:" so when
parsing "::" we can't tell how many half words to skip.

Changes in v2:
- Wrap code in CONFIG_NET6

 include/net6.h  |   3 ++
 lib/net_utils.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)

diff --git a/include/net6.h b/include/net6.h
index 1b82c25..a41eb87 100644
--- a/include/net6.h
+++ b/include/net6.h
@@ -58,4 +58,7 @@ static inline int ipv6_addr_is_isatap(const struct in6_addr 
*a)
        return (a->s6_addr32[2] | htonl(0x02000000)) == htonl(0x02005EFE);
 }
 
+/* Convert a string to an ipv6 address */
+int string_to_ip6(const char *s, struct in6_addr *addr);
+
 #endif /* __NET6_H__ */
diff --git a/lib/net_utils.c b/lib/net_utils.c
index f148b8a..7422c27 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -11,6 +11,8 @@
  */
 
 #include <common.h>
+#include <net6.h>
+#include <linux/ctype.h>
 
 struct in_addr string_to_ip(const char *s)
 {
@@ -39,3 +41,122 @@ struct in_addr string_to_ip(const char *s)
        addr.s_addr = htonl(addr.s_addr);
        return addr;
 }
+
+#ifdef CONFIG_NET6
+/**
+ * Parses an struct in6_addr from the given string. IPv6 address parsing is a 
bit
+ * more complicated than v4 due to the flexible format and some of the special
+ * cases (e.g. v4 mapped).
+ *
+ * Examples of valid strings:
+ *   2001:db8::0:1234:1
+ *   2001:0db8:0000:0000:0000:0000:1234:0001
+ *   ::1
+ *   ::ffff:192.168.1.1
+ *
+ * Examples of invalid strings
+ *   2001:db8::0::0          (:: can only appear once)
+ *   2001:db8:192.168.1.1::1 (v4 part can only appear at the end)
+ *   192.168.1.1             (we don't implicity map v4)
+ */
+int string_to_ip6(const char *strpt, struct in6_addr *addrpt)
+{
+       int colon_count = 0;
+       int found_double_colon = 0;
+       int xstart = 0;         /* first zero (double colon) */
+       int len = 7;            /* num words the double colon represents */
+       int i;
+       const char *s = strpt;
+       struct in_addr zero_ip = {.s_addr = 0};
+
+       if (strpt == NULL)
+               return -1;
+
+       /* First pass, verify the syntax and locate the double colon */
+       for (;;) {
+               while (isxdigit((int)*s))
+                       s++;
+               if (*s == '\0')
+                       break;
+               if (*s != ':') {
+                       if (*s == '.' && len >= 2) {
+                               struct in_addr v4;
+                               while (s != strpt && *(s - 1) != ':')
+                                       --s;
+                               v4 = string_to_ip(s);
+                               if (memcmp(&zero_ip, &v4,
+                                          sizeof(struct in_addr) != 0)) {
+                                       len -= 2;
+                                       break;
+                               }
+                       }
+                       /* This could be a valid address */
+                       break;
+               }
+               if (s == strpt) {
+                       /* The address begins with a colon */
+                       if (*++s != ':')
+                               /* Must start with a double colon or a number */
+                               goto out_err;
+               } else {
+                       s++;
+                       if (found_double_colon)
+                               len--;
+                       else
+                               xstart++;
+               }
+
+               if (*s == ':') {
+                       if (found_double_colon)
+                               /* Two double colons are not allowed */
+                               goto out_err;
+                       found_double_colon = 1;
+                       len -= xstart;
+                       s++;
+               }
+
+               if (++colon_count == 7)
+                       /* Found all colons */
+                       break;
+       }
+
+       if (colon_count == 0)
+               goto out_err;
+       if (*--s == ':')
+               len++;
+
+       /* Second pass, read the address */
+       s = strpt;
+       for (i = 0; i < 8; i++) {
+               int val = 0;
+               char *end;
+
+               if (found_double_colon && i >= xstart && i < xstart + len) {
+                       addrpt->s6_addr16[i] = 0;
+                       continue;
+               }
+               while (*s == ':')
+                       s++;
+
+               if (i == 6 && isdigit((int)*s)) {
+                       struct in_addr v4 = string_to_ip(s);
+                       if (memcmp(&zero_ip, &v4,
+                                  sizeof(struct in_addr)) != 0) {
+                               /* Ending with :IPv4-address */
+                               addrpt->s6_addr32[3] = v4.s_addr;
+                               break;
+                       }
+               }
+
+               val = simple_strtoul(s, &end, 16);
+               if (*end != '\0' && *end != ':')
+                       goto out_err;
+               addrpt->s6_addr16[i] = htons(val);
+               s = end;
+       }
+       return 0;
+
+out_err:
+       return -1;
+}
+#endif
-- 
2.5.3

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